Export ⚡️

In case your project outgrows the cabapilities of Scala CLI (e.g support for modules) it may be beneficial to switch to a build tool such as SBT or Mill. The export sub-command allows to do that by converting a Scala CLI project into an SBT or Mill configuration. Additionally the sub-command supports the JSON format for custom analysis of projects.

Results of running the sub-command are, by default, put in ./dest/, that behaviour can be modified by specifying a path with the --output option.

caution

The export sub-command is restricted and requires setting the --power option to be used. You can pass it explicitly or set it globally by running: scala-cli config power true

The project configuration is read both from information specified in source files as well as options passed to the export sub-command.

Let's take a simple one-file project as an example:

Hello.scala

//> using scala "3.1.3"
//> using option "-Xasync"
//> using dep "com.lihaoyi::os-lib:0.9.0"

object Hello {
  def main(args: Array[String]): Unit =
    println(os.pwd)
}

Exporting to SBT:

scala-cli --power export Hello.scala --sbt

Note that --sbt is not required here since it's the default.

The result is an sbt-compliant project created in the dest/ directory:

dest
├── project
│   └── build.properties
├── src
│   └── main
│       └── scala
│           └── Hello.scala
└── build.sbt

All the project's configuration resides now in dest/build.sbt:

dest/build.sbt

scalaVersion := "3.1.3"

scalacOptions ++= Seq("-Xasync")

libraryDependencies += "com.lihaoyi" %% "os-lib" % "0.9.0" 

libraryDependencies += "com.lihaoyi" %% "os-lib" % "0.9.0" % Test

To configure the version of SBT used in the new project provide the --sbtVersion option to the export sub-command.

Exporting to Mill:

scala-cli --power export Hello.scala --mill --output=dest_mill

Mill is not the default export format, so passing the --mill option is required.

By specifying the path with --output option the results are now created in dest_mill/ directory:

dest_mill
├── project
│   └── src
│       └── Hello.scala
├── .mill-version
├── build.sc
├── mill
└── mill.bat

And all the project's configuration resides now in dest_mill/build.sc:

dest_mill/build.sc

import mill._
import mill.scalalib._
object project extends ScalaModule {
  def scalaVersion = "3.1.3"
  def scalacOptions = super.scalacOptions() ++ Seq("-Xasync")
  def ivyDeps = super.ivyDeps() ++ Seq(
    ivy"com.lihaoyi::os-lib:0.9.0"
  )

  object test extends Tests {
    def ivyDeps = super.ivyDeps() ++ Seq(
      ivy"com.lihaoyi::os-lib:0.9.0"
    )
  }
}

The script files mill and mill.bat are mill wrappers fetched from lefou/millw repository. To change the build tool version used override the contents of dest_mill/.mill-version.

Exporting to JSON:

To export project information in a human-comprehensible format, use the --json flag.

scala-cli --power export Hello.scala --json --output=dest_json

The result is the dest_json/export.json file:

dest_json/export.json

{
 "scalaVersion": "3.1.3",
 "platform": "JVM",
 "scopes": {
  "main": {
   "sources": [
    "Foo.scala"
   ],
   "scalacOptions": [
    "-Xasync"
   ],
   "dependencies": [
    {
     "groupId": "com.lihaoyi",
     "artifactId": {
      "name": "os-lib",
      "fullName": "os-lib_3"
     },
     "version": "0.9.0"
    }
   ],
   "resolvers": [
    "https://repo1.maven.org/maven2",
    "ivy:file:///Users/mgajek/Library/Caches/ScalaCli/local-repo/v0.1.20-111-648755-DIRTY2ba64fdc//[organisation]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext]",
    "ivy:file:/Users/mgajek/.ivy2/local/[organisation]/[module]/(scala_[scalaVersion]/)(sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext]"
   ]
  }
 }
}